The Cupertino Courier
News
Health risks linked to TCE at Superfund site reported
Water board says problems under control, being watched
By HUGH BIGGAR
A new report published by the National Academy of Sciences says a chemical found at some toxic waste sites, including one on the Cupertino/Sunnyvale border, might be more hazardous than originally thought. What that means for human health is an ongoing debate.
The chemical TCE, or trichloroethylene, is increasingly believed to have strong links to kidney cancer, the report says. Other potential health risks include liver cancer, reproductive and developmental problems, impaired neurological function and autoimmune disease.
According to the July 27 report by the NAS' National Research Council, "the evidence on carcinogenic and other health risks from trichloroethylene exposure has strengthened since 2001."
The San Francisco Bay Region Water Quality Control Board, though, says the local implications of such findings are premature.
"It could be years, not months, before we known anything," says John Wolfenden, spokesman for the water board, which oversees the Cupertino toxic waste site. "We would have to go back in and take samples in Cupertino. In the meantime, we don't expect any changes in cleanup."
Others are less certain
"The report is likely to have enormous implications for federal, state and private cleanup programs, because TCE is found in groundwater at thousands of contamination sites throughout the United States," said Lenny Siegel of Mountain View's Center for Public Environmental Oversight in a written response to the report.
Leslie Stayner, a University of Illinois-Chicago epidemiologist who worked on the report, said in an email that past TCE exposure is also a factor. "For cancer, we generally expect that it will be related to exposures that occurred 10 to 20 years previously," she said.
In Santa Clara County, Wolfenden says the report's findings are difficult to gauge.
"The contamination for almost all of the sites in Santa Clara Valley is in the shallow groundwater zones, which are not currently used for [tap] water," he said.
Tap water in the county is drawn from deep underground aquifers and then processed through treatment plants, re-charge ponds and reservoirs. Improperly abandoned wells with cracked casings, though, would make it possible for groundwater to seep into the deeper aquifers, experts say.
Although contaminants at the Cupertino may have affected groundwater used in water supplies more than 20 years ago, the water board says the pollution has since been contained.
Who may be at risk
The water board is now at work monitoring and cleaning a groundwater contamination plume from the site extending north to Inverness Way in Sunnyvale and just south of Forge Drive in Cupertino. Penelope McDaniel of the Environmental Protection Agency also said it extends slightly west of the Superfund site at 10900 Tantau Ave. Typically, exposure occurs from ingestion or inhalation of steam, such as in the shower. With small amounts of TCE at a site, inhalation would have to occur over a long period.
Cleanup in the area has been under way since the mid-1980s. After its designation as a federal Superfund site in 1982--a priority list of the most toxic sites in the nation--former site owners Intersil and Siemens and the water board have scoured the area to remove contaminants, including TCE. Intersil and Siemens used the chemical as a solvent in semiconductor manufacturing. Chemical waste was stored in underground tanks that leaked or spilled. Cleanup work has included removing, vaporizing and treating soil and pumping out contaminated groundwater. Intersil and Siemens also removed the leaky underground storage tanks and have ceased operations at those sites.
Improvements seen
The water board says the efforts are paying off, though they could take up to 300 years. In the interim, they say, contaminants tend to adhere to low-permeability clay soil at the site. "The risks there are negligible," said Stephen Hill, who oversees toxic waste clean up for the water board.
Whether that risk assessment will change as a result of the new findings on TCE is unknown.
Asked if additional tests or a health survey had been scheduled as a result of the report, Wolfenden said , "That's a little bit hard to answer. None that I'm aware of, but Santa Clara is a big county with many companies and agencies."
"There are a number of steps to take and we can't predict what will happen," said Elizabeth Allen, a toxicologist for the water board.
In the meantime, the report does say there is mounting evidence linking kidney cancer to TCE. Statistics from the Northern California Cancer Center show Santa Clara County, home to the most Superfund sites per county in the nation--29--had the highest rate of kidney cancer in the Bay Area between 1998 and 2002.
